This application claims priority to PCT Application No. PCT/JP00/04551, filed Jul. 7, 2000, which claims the benefit of Japanese Application No. 11-192928, filed Jul. 7, 1999. Both PCT Application No. PCT/JP00/04551 and Japanese Application No. 11-192928 are incorporated herein by reference to the extent permitted by law.
1. Technical Field
This invention relates to a method and apparatus for fabricating an organic EL (electroluminescence) display utilized as a panel light source, a display panel or the like, and particularly to a method and apparatus which enables continuous and efficient fabrication of a flexible organic EL display having a cathode, a luminescent layer made of an organic substance and an anode on an optically flexible substrate.
2. Background Art
An organic EL element is an element of a thin film type having a first electrode (anode or cathode) formed on a substrate, an organic layer (single layer portion or organic multilayer portion), that is, a luminescent layer, containing an organic luminescent substance stacked thereon, and a second electrode (cathod or anode) stacked on the luminescent layer. In this organic EL element, the organic luminescent substance is caused to emit light by applying a predetermined voltage between the first electrode and the second electrode.
Since the organic EL element is an element of a thin film type as described above, when an organic EL panel having a single or a plurality of organic EL elements formed on the substrate is used as a panel light source of black light or the like, an apparatus having the panel light source can be easily thinned. Moreover, when a display device is constituted by using, as a display panel, an organic EL panel having a predetermined number of organic EL elements as pixels formed on a substrate, advantages that cannot be provided by a liquid crystal display device are realized such as high visibility and absence of field angle dependency.
However, in the case of fabricating an organic EL element, there remain many technical problems and it is generally difficult to finely pattern the cathode or the luminescent layer (organic EL medium layer) of the organic EL element because of the poor heat resistance (in general, 100xc2x0 C. or lower), low solvent resistance and poor moisture resistance of the organic substance (organic EL medium) used for a charge injection layer and a luminescent layer. For example, it is very difficult to use a photolithography method, which is normally used for patterning of a thin film, for the organic EL element because there is a problem of deteriorating characteristics of the organic EL element due to the entry of a solvent in a photoresist into the element, the high-temperature atmosphere in a resist baking step, the entry of a resist developer solution or an etching solution into the element, the damage by plasma in dry etching and the like.
As a technique for solving the foregoing problems, an organic EL panel having little deterioration in an organic EL element and having high reliability and a fabrication method therefor are disclosed in the Japanese Publication of Unexamined Patent Application No. H9-102393.
As a technique for inexpensive and efficient mass production of organic EL displays as described in the above-mentioned publication, a method and apparatus of a so-called roll-to-roll system may be considered. However, this technique has not been sufficiently studied yet, and considerably complicated steps and device structure are required for fabricating a flexible organic EL display by the roll-to-roll system. For example, in the current state, it is quite difficult to pattern a cathode or a luminescent layer for the organic EL element at a low cost on a substrate of a large area made of a plastic film or the like.
Thus, it is an object of the present invention to provide a method and apparatus for fabricating an organic EL display by the roll-to-roll system, which enables continuous and efficient mass production of flexible organic EL displays.
In order to achieve the above-described object, a method for fabricating a flexible organic EL display according to a first aspect of the present invention is adapted for fabricating an organic EL display having a cathode, a single or a plurality of luminescent layers made of an organic substance, and an anode provided on an optically transparent substrate, wherein a strip-like flexible substrate made of a plastic film or the like is used as the optically transparent substrate, and a step of patterning the luminescent layer and a step of patterning the cathode are carried out in a vacuum by a roll-to-roll system while making the flexible substrate travel continuously.
As the luminescent layer patterning step according to the first aspect of the present invention, it is preferred to pattern the luminescent layer on the surface of the flexible substrate on which the anode is patterned in advance and to clean the surface of the flexible substrate by ion bombardment immediately before the luminescent layer patterning step.
Also, according to the first aspect of the present invention, it is preferred that at least one of the luminescent layer patterning step and the cathode patterning step is carried out by vacuum vapor deposition or sputtering using a mask having an opening portion of a predetermined shape formed therein, and is adapted for forming a stripe pattern having a width equal to the width of the opening portion on the flexible substrate.
Moreover, according to the first aspect of the present invention, it is preferred that as the mask, a strip-like mask having opening portions intermittently formed therein is caused to intermittently travel by the roll-to-roll system at every predetermined travelling length of the flexible substrate in accordance with the roll-to-roll system, and that the opening portions which are reeled out are caused to face a generation source of a patterning substance in the luminescent layer patterning step and the cathode patterning step.
Furthermore, according to the first aspect of the present invention, it is preferred that a tracking signal is provided on one lateral end portion of the flexible substrate, the position in the longitudinal direction and the direction of the width of the flexible substrate is detected by detecting the tracking signal, and the position of the opening portion formed in the mask and the opening and closing timing of a shutter for starting and stopping the supply of the patterning substance to the flexible substrate are controlled on the basis of the result of detection.
In addition, according to the first aspect of the present invention, it is preferred that the flexible substrate processed in the luminescent layer patterning step and the cathode patterning step is wound in a roll shape and that the roll is housed in a container filled with an inert gas and is carried to the next step.
In order to achieve the above-described object, a method for fabricating a flexible organic EL display according to a second aspect of the present invention is adapted for fabricating an organic EL display having a cathode, a single or a plurality of luminescent layers made of an organic substance, and an anode provided on an optically transparent substrate, wherein a strip-like flexible substrate made of a plastic film or the like is used as the optically transparent substrate, and a step of patterning the luminescent layer and a step of patterning the cathode are carried out in a vacuum by a roll-to-roll system while making the flexible substrate travel intermittently.
In order to achieve the above-described object, an apparatus for fabricating a flexible organic EL display according to a third aspect of the present invention is adapted for fabricating an organic EL display having a cathode, a single or a plurality of luminescent layers made of an organic substance, and an anode provided on an optically transparent flexible substrate made of a plastic film or the like, wherein a step of patterning the luminescent layer and a step of patterning the cathode onto the surface of a strip-like optically transparent flexible substrate are carried out in a vacuum by a roll-to-roll system while making the flexible substrate travel continuously.
According to the third aspect of the present invention, it is preferred to provide an ion cleaning electrode for cleaning the surface of the flexible substrate by ion bombardment immediately before the luminescent layer patterning step.
Also, according to the third aspect of the present invention, it is preferred that at least one of the luminescent layer patterning step and the cathode patterning step is carried out by vacuum vapor deposition or sputtering using a mask, and that the apparatus includes a continuously rotating drum for winding the flexible substrate thereon and causing the flexible substrate to travel, a generation source of a patterning substance, and a mask arranged between the continuously rotating drum and the patterning substance generation source and having an opening portion of a predetermined shape formed therein.
Moreover, according to the third aspect of the present invention, it is preferred that the apparatus includes travelling means for causing a strip-like mask, having opening portions intermittently formed therein to intermittently travel by the roll-to-roll system at every predetermined travelling length of the flexible substrate in accordance with the roll-to-roll system, and that the opening portions reeled out by the travelling means are caused to face the generation source of the patterning substance.
Furthermore, according to the third aspect of the present invention, it is preferred that the apparatus includes a tracking signal provided on one lateral end portion of the flexible substrate and a tracking signal detection sensor for detecting the tracking signal, and that the position in the longitudinal direction and the direction of the width of the flexible substrate is detected by detecting the tracking signal using the tracking signal detection sensor, and the position of the opening portion formed in the mask and the opening and closing timing of a shutter for starting and stopping the supply of the patterning substance to the flexible substrate are controlled on the basis of the result of detection.
In addition, according to the third aspect of the present invention, it is preferred that the apparatus includes winding means for winding in a roll the flexible substrate, processed in the luminescent layer patterning step and the cathode patterning step, and a container filled with an inert gas for housing the roll.
Further, according to the third aspect of the present invention (FIGS. 1 and 2), it is preferred that a travelling counter 12 for counting the travelling distance of a flexible substrate 1 and an anode pattern edge detection sensor 27 for detecting an edge 4a of an anode stripe pattern 4 (having streak-shaped anode patterns formed in a plurality of rows along the direction of width of the flexible substrate 1) are provided in the luminescent layer patterning step constituting the apparatus for fabricating a flexible organic EL display, and that a shutter 24 for starting and stopping the supply of the patterning substance to the flexible substrate 1 and a shutter controller 25 for controlling the opening and closing of the shutter 24 are provided in a patterning substance generation source (evaporation source) 23, wherein the travelling counter 12 and the anode pattern edge detection sensor 27 are caused to communicate with the shutter controller 25 and wherein patterning from a front end portion to a rear end portion of the anode stripe pattern 4 along the substrate travelling direction is carried out by controlling the opening and closing of the shutter 24 in the luminescent layer patterning step.
Moreover, according to the third aspect of the present invention (FIGS. 1 and 2), it is preferred that the luminescent layer patterning step for forming a luminescent layer pattern 6 (and 7) of another color in parallel with and distanced away at an appropriate space from a luminescent layer pattern 5 in the flexible substrate 1 having the anode stripe pattern 4 formed in the direction of width of the flexible substrate 1 and having the luminescent layer stripe pattern 5 of a predetermined color orthogonal to the anode pattern 4, or the cathode patterning step for stacking a stripe pattern 8 of a cathode 8a on luminescent layer stripe patterns 5, 6, 7 in the flexible substrate 1 having the anode stripe pattern 4 formed in the direction of width of the flexible substrate 1 and having the luminescent layer stripe patterns 5, 6, 7 of predetermined colors formed on the anode pattern 4, is constituted as follows.
That is, it is preferred that a travelling counter 12 for counting the travelling distance of the flexible substrate 1, an anode pattern edge detection sensor 27 for detecting an edge 4a of the anode stripe pattern 4, luminescent layer pattern edge detection sensors 42, 52, 62 for detecting edges 5a, 6a, 7a of the luminescent layer patterns 5, 6, 7, a mask width position controller 45 for adjusting the position of a mask 28 in the direction of width of the flexible substrate, and an edge position controller 41 for correcting meandering of the flexible substrate 1 on the continuously rotating drum (for example, first cooling can 21) are provided. It is also preferred that the anode pattern edge detection sensor 27 is caused to communicate with a shutter controller 25, the travelling counter 12 is caused to communicate with the shutter controller 25 and the mask width position controller 45, and the luminescent layer pattern edge detection sensor 42 is caused to communicate with the mask width position controller 45. It is also preferred that a shutter 24 for starting and stopping the supply of the patterning substance to the flexible substrate, and the shutter controller 25 for controlling the opening and closing of the shutter 24 are provided in the patterning substance generation source.
In order to achieve the above-described object, an apparatus for fabricating a flexible organic EL display according to a fourth aspect of the present invention is adapted for fabricating an organic EL display having a cathode, a single or a plurality of luminescent layers made of an organic substance, and an anode provided on an optically transparent flexible substrate made of a plastic film or the like, wherein a step of patterning the luminescent layer and a step of patterning the cathode onto the surface of a strip-like optically transparent flexible substrate are carried out in a vacuum by a roll-to-roll system while making the flexible substrate travel intermittently.